The Spanish has three kinds of demonstrative, whose use depends on the distance between the speaker and the described thing/person.

Demonstratives

Near

Middle

Far

Masculine singular

este

ese

aquel

Masculine plural

estos

esos

aquellos

Feminine singular

esta

esa

aquella

Feminine plural

estas

esas

aquellas

English also used to have a three-way system: "this hill (here)", "that hill (there)" or "yon hill (yonder)" — in Spanish, "esta colina", "esa colina", "aquella colina". Standard English lost the third level, so that the "that, there" series covers the ground of "yon, yonder".

Este usually refers to something near the speaker (the first person). Ese usually refers to something nearer the hearer (the second person). Aquel usually refers to something away from both the speaker and the hearer.

The demonstrative determiners can also be used as pronouns, with the addition of the neutral singular forms esto, eso, aquello.

The definite article in Spanish, corresponding to "the", is el. It agrees for gender and number as follows:

el hombre = "[the] man"

los hombres = "[the] men"

la mujer = "[the] woman"

las mujeres = "[the] women"

The usually masculine form el is used instead of la before feminine nouns beginning with a stressed a sound:

el águila (pequeña)

el agua (fresca)

el hacha (afilada)

Exceptions: la is used despite this when use of el would imply a man:

la ácrata (because el ácrata would be a male anarchist)

la árabe (because el árabe would be a male Arab, or the Arabic language)

Azúcar is a very special case. Its a- is unstressed, and yet it usually takes el even when feminine; in addition, azúcar can be of both genders in Spanish (other words with double gender are sal (salt), mar (sea) and sartén (frying pan)):

N.B.: this feminine el does not have the same origin as the masculine el. The latter is from the Old Castilian ele, whereas the former is from ela, just as la is. This historic finesse is lost to those who use non-standard forms such as los águilas.

There is also a "neuter article", used before adjectives, that make them work like nouns:

These are often known as possessive or genitive determiners. They are used before the noun they possess (and before the rest of the whole noun phrase, for example when an adjective precedes the noun). They agree in number with the noun, and sometimes in gender, too.

1st person singular (yo): mi(s)

2nd person singular (tú): tu(s)

3rd person singular (él, ella): su(s)

1st person plural (nosotros/as): nuestro/a(s)

2nd person plural(vosotros/as): vuestro/a(s)

3rd person plural (ellos/as): su(s)

Note the following:

There is no distinction in number for the third person possessives (i.e. between "his"/"her"/"its" and "their").

The possessive for usted and ustedes is su(s) as for other third-person pronouns. The ambiguity that this causes (especially considering that su(s) already covers "his", "her", "its" and "their") can be allieviated by treating usted(es) as a noun and thereby saying la casa de ustedes instead of su casa. It is also possible to disambiguate by saying la casa de él or la casa de ella, etc.

Dialectal variation:

The archaic pronoun vos has the possessive form vuestro, just like vosotros does. However, in modern dialectal use, tu replaces vuestro. Therefore, an Argentinian would say Che, decime tu dirección rather than decidme vuestra dirección or dime tu dirección.

Strictly speaking, the presence of the first determiner means that the possessive must be interpreted as an adjective rather than a determiner. Note however that the normal adjectival form (mío, tuyo, suyo...) is not used in this construction.

It is also possible to use the normal adjectival form. In this case, it goes after the noun.